Year	Percent
1990	61.17
1991	61.28
1992	61.3
1993	61.36
1994	61.55
1995	61.41
1996	61.05
1997	60.5
1998	60.49
1999	60.59
2000	60.13
2001	59.74
2002	59.62
2003	59.37
2004	59.13
2005	59.5
2006	59.32
2007	58.86
2008	58.49
2009	58.6
2010	58.35
2011	58.23
2012	58.66
2013	59.35
2014	59.44
2015	59.62
2016	60.14
2017	60.46
2018	60.77
2019	60.5
2020	59.67